Railway hopper cars with one or more hoppers have been used for many years to transport and sometimes store dry, bulk materials. Hopper cars are frequently used to transport coal, sand, metal ores, ballast, aggregates, grain and any other type of lading which may be satisfactorily discharged through respective openings formed in one or more hoppers. Respective discharge openings are typically provided at or near the bottom of each hopper to rapidly discharge cargo. A variety of door assemblies and gate assemblies along with various operating mechanisms have been used to open and close discharge openings associated with railway hopper cars.
Hopper cars may be classified as open or closed. Hopper cars may have relatively short sidewalls and end walls or relatively tall or high sidewalls and end walls. The sidewalls and end walls of many hopper cars are typically reinforced with a plurality of vertical side stakes. The sidewalls and end walls are typically formed from steel or aluminum sheets. Some hopper cars include interior frame structures or braces to provide additional support for the sidewalls.
Applicable standards of the Association of American Railroads (AAR) established maximum total weight on rail for any railcar including box cars, freight cars, hopper cars, gondola cars, and temperature controlled cars within prescribed limits of length, width, height, etc. All railway cars operating on commercial rail lines in the U.S. must have exterior dimensions which satisfy associated AAR clearance plates. Therefore, the maximum load which may be carried by any railcar is typically limited by the applicable AAR clearance plate and empty weight of the railcar. Reducing the empty weight of a railcar or increasing the interior dimensions may increase both volumetric capacity and maximum load capacity of a railcar while still meeting applicable AAR standards for total weight on rail and clearance plate.
Prior systems for opening and closing gates on hopper cars often include additional linkages that operated in co-planes and in perpendicular planes that required greater operating forces and greater complexity. Some prior art systems include torque tubes and other types of tension members.